Coherent sources are sources of light with a constant phase difference. The conditions for this are that there is a constant phase difference and that the light is of the same wavelength.
Relation between phase difference and path difference is path difference/wavelength=phase difference/2*pi
Yes, there a difference between three phase and single phase electrical supply services.
No, the phase difference between the nodes produced by two violins is not constant and so the interference is not possible.
If their phase difference is constant, then they don't produce light and dark patterns. Light spots are produced where the two sources are in phase, and dark spots where they're out of phase.
What is the difference between cw and steady at lock-on phase? I don't know.
You can measure the phase difference between 2 pendulums by measuring the distance between the two. The amount it comes out to will be the difference.
a phase is a region with homogeneous (uniform) properties and a conversion between states is called a "phase transition"
Single phase has one phase. Three phase has three phases.
Yes, there is a difference between single phase and three phase circuits.
"USE "? If you mean energy consumption, there is no difference.